Course Content

Introduction to SQL

1. Retrieving Data

Retrieving Individual Columns Retrieving Multiple Columns Retrieving All Columns Retrieving Distinct Rows Limiting Results Challenge: Find the Population of the Countries Challenge: Find All Countries Challenge: Find All Countries With Their IDs Challenge: Find Country Capitals Challenge: Find the Regions in Which All Countries Are Located

2. Sorting Retrieved Data

Sorting Data Challenge: Population Sort Sorting by Multiple Columns Challenge: Dual-Sort Query Specifying Sort Direction Challenge: Sort the Countries by Region and Capital Challenge: Sort Capitals in Descending Order Challenge: Sort Countries in Ascending Order Challenge: Find Countries, Their IDs, and Their Populations Challenge: Find Countries, IDs, Populations, Regions, and Sort Them Challenge: Find All Continents and Sort Them in Ascending Order

3. Filtering Data

Using the WHERE Clause Challenge: North America Population Sort The WHERE Clause Operators Challenge: Population Threshold Query Checking for a Range of Values Checking for NO Value

4. Advanced Data Filtering

Using the AND Operator Challenge: Europe Region Sort Using the OR operator Challenge: America Regions Filter Using the NOT Operator Challenge: Non-Europe Capitals Sort

5. Aggregate Functions

The AVG() Function Challenge: Surface Area Selection The COUNT() Function Challenge: Continental Count The MAX() Function The MIN() Function Challenge: Large Surface Area Average The SUM() Function

Sorting by Multiple Columns

We can also sort by multiple columns. We need to specify the column names separated by commas.

The first column specified in the sorting will have priority, and then the sorting will proceed according to the second column.

The syntax will look like this:

Let’s look at the example that retrieves three columns and sorts the results by two of them: first by population and then by capital:


              123
            
SELECT ID, population, capital 
FROM country 
ORDER BY population, capital;

Here is the country table we are working with:

Task

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Write an SQL query to retrieve four columns using the SELECT statement, namely: continent, region, population, and capital (please retrieve these columns in this order). Then, sort the result by two of them: first by continent, then by population.

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Section 2. Chapter 3

Sorting by Multiple Columns

We can also sort by multiple columns. We need to specify the column names separated by commas.

The first column specified in the sorting will have priority, and then the sorting will proceed according to the second column.

The syntax will look like this:

Let’s look at the example that retrieves three columns and sorts the results by two of them: first by population and then by capital:


              123
            
SELECT ID, population, capital 
FROM country 
ORDER BY population, capital;

Here is the country table we are working with:

Task

Swipe to show code editor

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 3

Sorting by Multiple Columns

We can also sort by multiple columns. We need to specify the column names separated by commas.

The first column specified in the sorting will have priority, and then the sorting will proceed according to the second column.

The syntax will look like this:

Let’s look at the example that retrieves three columns and sorts the results by two of them: first by population and then by capital:


              123
            
SELECT ID, population, capital 
FROM country 
ORDER BY population, capital;

Here is the country table we are working with:

Task

Swipe to show code editor

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Everything was clear?

Thanks for your feedback!

We can also sort by multiple columns. We need to specify the column names separated by commas.

The first column specified in the sorting will have priority, and then the sorting will proceed according to the second column.

The syntax will look like this:

Let’s look at the example that retrieves three columns and sorts the results by two of them: first by population and then by capital:


              123
            
SELECT ID, population, capital 
FROM country 
ORDER BY population, capital;

Here is the country table we are working with:

Task

Swipe to show code editor

Switch to desktop for real-world practiceContinue from where you are using one of the options below

Section 2. Chapter 3

Switch to desktop for real-world practiceContinue from where you are using one of the options below